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HTMLmarkup~8 mins

Self-closing tags in HTML - Performance & Optimization

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Performance: Self-closing tags
LOW IMPACT
Self-closing tags affect the parsing speed and DOM construction during page load.
Writing empty HTML elements efficiently
HTML
<img src="image.jpg" />
<br />
<input type="text" />
Self-closing tags are valid for void elements, allowing the browser to parse and build the DOM faster without corrections.
📈 Performance GainReduces parsing overhead and speeds up DOM construction
Writing empty HTML elements efficiently
HTML
<img src="image.jpg">
<br>
<input type="text">
Using separate closing tags for void elements is invalid HTML and can cause the browser to re-parse or fix the markup, slowing parsing.
📉 Performance CostTriggers extra parsing steps and potential reflows during DOM construction
Performance Comparison
PatternDOM OperationsReflowsPaint CostVerdict
Incorrect closing tags on void elementsExtra parsing and DOM fixesPossible reflows if DOM is correctedMinimal[X] Bad
Proper self-closing tags for void elementsStraightforward DOM creationNo extra reflowsMinimal[OK] Good
Rendering Pipeline
Self-closing tags simplify the HTML parsing stage by clearly marking void elements, allowing the browser to build the DOM tree without guesswork or corrections.
HTML Parsing
DOM Construction
⚠️ BottleneckHTML Parsing
Core Web Vital Affected
LCP
Self-closing tags affect the parsing speed and DOM construction during page load.
Optimization Tips
1Always use self-closing syntax for void elements like <img />, <br />, <input />.
2Avoid separate closing tags on void elements to prevent parsing errors.
3Correct self-closing tags help browsers build the DOM faster and improve page load speed.
Performance Quiz - 3 Questions
Test your performance knowledge
Why should void elements like <img> use self-closing tags in HTML?
ATo add extra styling options
BTo help the browser parse HTML faster and avoid re-parsing
CTo increase the size of the HTML file
DTo make the page load slower
DevTools: Elements
How to check: Open DevTools, inspect the HTML elements, and verify void elements like <img>, <br>, <input> are self-closed properly.
What to look for: Look for warnings or automatic fixes in the Elements panel indicating invalid closing tags.